1. Field of the Invention
The present invention relates to a method and an apparatus for grinding a magnetic member, and a method and an apparatus for treating waste fluid. More specifically, the present invention relates to a method and an apparatus for grinding a magnetic member and a method and an apparatus for treating waste fluid in which waste grinding fluid containing sludge as waste of grinding is purified and reused.
2. Description of the Related Art
A related art for purifying the grinding fluid is disclosed in the Japanese Patent Laid-Open No. 10-309647. According to this related art, the grinding fluid containing impurities is stored in a tank, agitated by a nozzle for separation of sludge and abrasive grain from the grinding fluid. Then, the sludge is picked out of the tank by a magnet separator.
Another related art is disclosed in the Japanese Patent Laid-Open No. 8-299717. According to this related art, a filter is used for purification of the grinding fluid.
However, according to the former related art, small particles in the sludge cannot be removed sufficiently. If the small particles in the sludge are to be removed sufficiently, a large-capacity tank of about 3000 liters is required per apparatus, leading to a problem that the apparatus has to be large.
The sludge produced by grinding the magnetic member, particularly by grinding a rare-earth alloy, contains fine particles having a diameter of approximately 2 μm to 3 μm. According to the latter related art, the filter is often clogged by these particles, making difficult to efficiently remove the sludge containing these fine particles.
Further, if the grinding fluid is reused without sufficient removal of the sludge, when cutting the magnetic member by a grinding blade including heat resistant resin and super hard abrasive grain, a grinding edge wears prematurely.